Don't forget to restart Apache at this point to reload the php.ini changes.

The actual files for PHPUnit will likely live at:

/Applications/MAMP/bin/php5.3/share/pear/PHPUnit

This is where you will find Autoload.php and Framework.php.

Running SilverStripe Unit Tests

You should now be able to browse to /dev/tests/ in order to run some SilverStripe unit tests. You should see some output regarding how many tests were run, which passed and which failed. This was not appearing for me and the reason was because my MySQL user did not have the necessary permissions to create a temporary MySQL table.

So, if you are debugging issues here, and notice that there are no errors being reported in log files for Apache etc. make sure you have PHP error reporting turned on!